A free-for-all destroyed the Republican Party. Could Democrats be next?

I’ve been in Los Angeles this week, where the young and telegenic mayor, Eric Garcetti, is actively mulling a run for the Democratic presidential nomination — unless of course California decides to secede, in which case maybe he’ll settle for running a breakaway republic.

In years past, it would have been hard to imagine what Garcetti might be thinking. The only mayors who’ve run for president in either party (John Lindsay, Rudy Giuliani) have come from New York, where at least you get a national spotlight, and the results have been wretched.

But there’s a feeling in Democratic politics that anything’s possible in 2020, and maybe anything is. Mayors and rappers, movie stars and moguls, Oprah and Kanye — all of them are eyeing (or at least pretending to eye) a leaderless party whose ballot line is up for grabs, along with a celebrity president who proved that you no longer need the right résumé — or any résumé at all, really — to take over a party.

If half the untested politicians and zillionaires who’ve signaled some interest in the Democratic nomination actually follow through, we’ll have to turn around the debating halls so it’s the moderators who sit on the dais and the candidates who pack the house.

All of which might be good for Democrats, whose public brand could certainly use a little reimagining. But I see a very real danger here for them, which is that if no one in the upper echelons of the party starts thinking about how to contain this field, they might be setting themselves up to relive the Republican experience of 2016.

Believe me, I get why Democrats seem excited about the idea of an unprecedented free-for-all. Last time out, the party’s governing apparatus rallied fiercely to the side of the establishment favorite and actively sought to marginalize resistance. Look where it got them.

Democrats have concluded, reasonably, that there’s a lesson to be learned from the last war, which is that the establishment can no longer dictate choices to the electorate and expect to win.

It’s possible, though, that you can overlearn one lesson of the 2016 campaign while completely failing to take note of another.

Start with this: Why did Donald Trump win the Republican nomination, and why did all of his adversaries look so small and feckless in comparison?

I guess you could argue it’s because he was such a magnetic salesman, or because the entire Republican Party is nativist and reactionary. I don’t think either of those things is true.

No, as I’ve written before, Trump won the war of attrition because the rest of the more conventional field was so impossibly fractured and muddled that having an unshakable 25 or 30 percent of the vote behind him was enough to get him through. And there are structural reasons it happened this way.

In years past, if you were a governor or senator who wanted to become president, you generally wouldn’t just declare yourself a candidate and dive in. The limited base of supporters in your own state, where people knew you, wasn’t enough to bankroll an entire campaign.

If you were serious about winning, you needed to convince a bunch of other governors or senators to swing their support behind you, thus tapping into their supporters, too. Which is why we never saw more than a couple of governors running for president at the same time; the rules had a way of naturally winnowing the field.

But then came the advent of the so-called super-PAC, with unlimited contributions. Now, if you had even one wealthy supporter who was willing to write you a series of checks, or if you had that kind of fortune yourself, you could afford to run for president whether anyone other than your spouse thought it was a good idea or not.

I remember when a longtime Republican strategist told me, back in the summer of 2015, that before the primaries started the field would shake itself out, and the party would have no more than six or seven candidates, like it always had before.

In the end, though, Republicans had that many governors alone, and none of them went anywhere. It wasn’t that governors had suddenly become less compelling candidates; it was that no one could really tell the lot of them apart, and all they managed to do (along with a bunch of similarly obscure senators) was to divide the large majority of the electorate among them.

Meanwhile, there was Trump, a TV star with built-in name recognition, whipping up rage and dominating coverage. Trump didn’t command more than a third of primary voters until his nomination was a fait accompli, but that third was more than enough.

The lesson is this: When a field is divided 20 different ways among a bunch of candidates who cancel each other out, the candidate who makes a loud, emotional or even outrageous appeal can incite enough of a disenchanted plurality to win.

Now, I know what Democrats are going to say to this, which is that their electorate believes in governing experience, and they don’t have a candidate who is as odious as Trump. No one’s going to solidify a quarter of the Democratic vote by preaching bigotry and failing to demonstrate even a passing knowledge of policy.

Which may be true (I’m less sure about that last one), except that the party does have its own brand of angry populism, and it’s just as rage-filled and backward-looking as populism on the right. It’s anti-trade, isolationist and nostalgic. It offers no way forward that doesn’t wind its way back through the 1930s.

Leftists like Bernie Sanders and Elizabeth Warren are nowhere near Trump when it comes to sheer depravity and ignorance, but they are just as capable of offering simplistic and dated answers for modern problems.

And those are the raging populists with some actual governing legitimacy. Don’t think for a second that a nonpolitician making that same appeal in even starker language — the Rock, Chris Rock, some other rock — can’t lock down 20 percent of the vote from day one, while everyone else scuffles to decide who gets to debate in primetime.

I’m not sure what you do to head off this dynamic. I’m certainly not suggesting that the party’s national chairman or its legislative leaders try to game the process, the way they did in 2016. It’s not right, and it probably isn’t possible now.

But if I were an elite Democratic contributor or one of the party’s senior governors, I’d be thinking about how to build early support around a candidate I believed could win and govern. I’d at least try to shape a field where the influential governing blocs of the party — governors, mayors, senators — arrayed behind a couple of candidates with widespread support.

Absent that, these days, you risk becoming a ballot line to be borrowed by some outside agitator. And just because it happened to the other guys last time doesn’t mean it can’t happen to you.